To study the properties and control mechanisms of phosphofructokinase from the mammalian heart; to study the chemical and physical properties of crystalline heart phosphofructokinase and to compare these properties with those of other sources; to study the mechanisms of the regulation of glycogen synthesis and glycogen breakdown in the liver fluke and to compare these with those in mammalian tissues; to investigate the cellular and subcellular effects of serotonin and lysergic acid diethylamide on the liver fluke and to test the action of those agents in homologous mammalian systems; to test the possible role of serotonin as the hormone regulating carbohydrate metabolism in the liver fluke.